This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Detect activation of brown adipose tissue in mice either exposed to cold temperature or injected with norepirephrine. One animal will be stored in cold room for 5 hours before the FDG-PET scan. The other animal will be injected with norepirephrine prior to the FDG-PET scan. Both animals will be euthanized at end of the study.